A motor is a device that generates torque by using electromagnetic induction law and widely used as a driving means in most industrial fields such as robots, electric vehicles, industrial machines, and household applications.
The performance of a motor is generally divided into rotation speed and torque, and a motor controller is used to control the rotation speed and/or the torque in real time when operation speed of the device and/or the load are not constant.
A control method of the motor controller is divided into a variable voltage variable frequency (VVVF) control, a sensorless vector control, and a sensor feedback vector control, etc. In the fields requiring precise control such as robots, electric vehicles, and precision machines, the sensor feedback vector control has been generally applied.
The motor controller is generally used for each motor, and even in a device using several motors such as a multi-axis machine and a multi-axis robot, in many cases, a separate motor controller is connected to each motor and a main controller of the device is configured to transmit a control command for each motor controller.
However, in the multi-axis machine and the multi-axis robot, when the motor and the motor controller are installed one to one, the number of motor controllers increases, and thus, manufacturing costs increase and an installation space of the motor controllers needs to be ensured and thus, it is difficult to downsize the device.
Accordingly, a technology of individually controlling several motors by one motor controller has been developed recently. For example, Korean Patent No. 10-0665059 (patent 1) and No. 10-0718232 (patent 2) disclose a technology of branching a plurality of inverters (motor drivers) supplying power to each motor from one power supply source and controlling the plurality of inverters (motor drivers) by one motor controller, respectively.
However, when several motors are controlled by one motor controller, it is necessary to accurately control the operation of each motor in real time. Particularly, in the case of installing a separate motor for each drive wheel, such as an independent-drive electric vehicle, casualties may occur when a malfunction occurs, and thus, high control reliability is required.
The patent 1 and 2 above disclosed technology of enhancing control reliability by preventing noise due to interference between the inverters. However, by only the technology, it is difficult to implement a target speed stably under a severe condition in which an operation load is changed in real time and control to exhibit stable torque over a wide speed range.
Accordingly, in a field of an independent-drive electric vehicle, a multi-axis precision machine, and a multi-axis robot that simultaneously drive several motors to perform specific operations, it is necessary to develop a more precise control technique capable of exhibiting a stable torque over a range while controlling several motors by a single motor controller.
Meanwhile, researchers or developers of electric vehicles, multi-axis robots, multi-axis machine tools, and the like test the speed and torque of the motor while varying the control parameters of the motor controller during research and development. But, there are many difficulties in modifying or adding the control parameters, because most of the researchers are not familiar with the program installed on the motor controller,
In particular, since the control program installed in the motor controller corresponds to the trade secret of the manufacturer, in most cases, the control parameters are set by the manufacturer according to the request of the user. As a result, it is practically impossible to test the performance of the motor in various fields while variously changing the control parameters.
Therefore, there is a need to develop a motor controller that allows motor users or related researchers to more easily set or add the control parameters.